Ethanol DOES boost the octane...but understand that the initial fuel blending is SUB-GRADE!! The ethanol is used to make the sub-grade component meet spec....ie: 87 octane,89 octane...etc. The 2 major detrimental factors of ethanol are that 1.) It begins to break down at 30 days!! That is...30 days from the manufacture date...not the day it hits the gas station. So as much as I hate to say it....avoid the little out of the way mom and pop shops that don't see a lot of fuel sales.... 2.) Ethanol blends with water!!! It does NOT seperate out! It is imperative to use a good water remover on a regular basis. Water has NO lubricating qualities so it is extremely bad for fuel pumps, carbs, etc. Unfortunately ethanol is here to stay...... We have been told that as of Jan 2011 it will be in ALL gas stations statewide!....I can't say for a fact...but that is what I've been told. I work for a local refinery, and have seen first hand how bad this stuff is. Any of our equiptment that sees 100% ethanol, has all seals replaced on a monthly basis! This is some bad sh*t!